Wear trousers, not jeans (I'm assuming you own a pair of interview/work/funeral britches in amongst the combats) - it says smart dress preferred, so you might get away with jeans, but if you don't then you've wasted a day and your ticket.
Don't climb on stuff, no betting on your mobile, don't scare the horses, and stick to your own enclosure. Forget the rest - everyone else will.
Have fun, and don't bet your shirt (or your trousers........)